DE102012214203A1 - Method for position determination in radio network, involves determining signal characteristic of radio network at position by mobile end device, where information is derived from signal characteristic over this position - Google Patents

Abstract

The method involves determining signal characteristics (SC1,SC2) of the radio network (FN) at positions (P1,P2) by a mobile end device. An information is derived from the signal characteristics over these positions. Multiple probable current positions are determined from the signal characteristic at a time point. Probabilities for the current positions are derived from temporally adjacent position determinations. The probable positions are specified as current position.

Description

Technical area

The present invention relates generally to the field of radio communications. In particular, the present invention relates to a method for determining the position of a mobile terminal in a radio network. In this case, a signal characteristic of the radio network for this position is determined by the mobile terminal at a position in the radio network and derived therefrom information about this position.

State of the art

With a steadily increasing proliferation of mobile devices, e.g. Mobile phones, so-called smartphones, laptops or so-called tablet PCs, and by the widespread availability of digital transmission technologies such as e.g. Wireless LAN, UMTS, GPRS, etc.) has also grown a market for applications in which a user is supplied with location-relevant information or in which a location-specific information of the terminal is determined. For this reason, the importance of efficient and accurate localization of mobile terminals is becoming more and more important and, in particular, radio network positioning and location systems have become more and more popular in recent years.

Such applications are also referred to as location-based services. In this case, with the aid of position-dependent data, a user is e.g. selective, location-based information (e.g., advertising, tourism information, etc.) may be proactively provided (e.g., upon entering a particular zone), or the location-dependent data may be used to track device movements or inventory management. For position determination, the radio networks available at the position, such as e.g. Wireless LAN, UMTS, GPRS, GSM, etc. used.

Particularly in the area within buildings - the so-called indoor area - the development of suitable position detection methods based on radio technology is a challenge, since within buildings walls, furnishings, etc. considerably complicate or impossible common positioning techniques and procedures. However, especially in buildings and / or in combined indoor and outdoor areas (e.g., corporate premises, shopping centers, etc.), a variety of location-dependent or location-based applications such as home security and the like may occur. Guidance and / or guidance systems for finding rooms, objects, product offers, etc., information services or application in the field of workfloor management. In order to be able to carry out these applications sensibly, in particular in the indoor area, it is essential to be able to determine and query a position of a mobile terminal and, where appropriate, its user at each location of the building or area at any time.

Known methods for determining the position of a mobile terminal in a radio network are, for example, radio cell identification via base station or access node identification, triangulation via transit time measurements or the so-called Global Positioning System (GPS). A disadvantage of these concepts, however, is their great complexity, which can lead to high costs, for example, as well as - if necessary, in particular in the indoor area - great inaccuracy in determining the position.

A method for determining the position in a radio network is radio cell identification via base station or access node identification, which is used in particular for estimating a position of an outdoor mobile terminal in mobile networks according to the GSM standard or the CDMA standard. In this case, an identification and / or coordinates of those radio cell is used for determining the position in which the mobile terminal is currently logged. This method has the disadvantage that the accuracy of the position determination depends on a size and shape of the radio cell. That the smaller the radio cell, the more accurate the position determined, so e.g. a position determination by means of radio cell identification in the city area more accurate than in rural areas. Overall, however, the method is rather unsuitable for accurate positioning due to its high inaccuracy - especially for the indoor area.

Another method for determining the position is the triangulation with signal transit time measurement. Triangulation uses geometric properties of a triangle to estimate a position. The data or information for the calculation can be derived either from a lateration or angulations. In lateration, the position of an object is estimated by measuring distances to reference points, for example, in a radio network not directly measuring the distance, but from received signal strength, signal arrival time (ie, time of arrival (TOA) or time) of Flight (TOF)) or a difference of signal delay or time difference of arrival (TDOA) between the position of the mobile terminal and at least two reference positions (eg base stations of a mobile network, access node to the radio network, etc.) is derived.

When using the angle determination for the position determination, a so-called arrival angle or angle of arrival (AOA) of a signal is derived from the difference of the signal propagation times. From this, the position of the mobile terminal can be determined by cutting a plurality of so-called angular direction lines formed by the radius between the mobile terminal and the respective reference point in the radio network (e.g., base station, access node, etc.). When used for determining the position of mobile terminals in a radio network, however, proves the relatively large inaccuracy as a disadvantage. In the case of the different triangulation methods, in particular when used indoors, errors can be caused, for example, by due to attenuation in walls, due to phase cancellations and due to multiple propagation with multiple reflections, which can only be accommodated by complex and difficult positioning procedures.

Another method for determining the position of a mobile terminal is the use of the so-called Global Positioning System or GPS. In this case, however, appropriate software and / or hardware in the mobile terminal for the positioning is required. The position of the mobile terminal is determined by the mobile terminal itself and then forwarded to the respective radio network. The position is e.g. determined using any satellite-based positioning system. A special form is the so-called Assisted GNSS or, when using GPS, the so-called Assisted GPS, in which the auxiliary data necessary for determining the position are provided by the radio network. However, this method also has a relatively high inaccuracy in estimating the position, especially in the indoor area due to a poorer coverage by satellite signals. In addition, it is necessary for A-GPS that the terminal has the appropriate hardware and / or software for position determination.

Furthermore, for a position determination in a radio network, in particular for applications in the indoor area, a so-called radio frequency (RF) fingerprinting-based method can be used. In so-called RF fingerprinting characteristics - so-called fingerprints or fingerprints - such. Field strength values, received signal strength (RSS), etc. for an environment (e.g., corporate site, shopping center, etc.) collected in, for example, a database.

These characteristics (eg field strength plant, received signal strength (RSS), etc.) are then determined by a mobile terminal at the position to be determined, this measured characteristic of the radio network is compared with the collected characteristics and a current position of the mobile terminal is derived therefrom. In this method, which, for example, in the writings DE 10 2004 035 531 B4 or WO 2010/14692 A1 Based on the disclosed positioning method, some environment or position dependent characteristics of a signal are used to estimate the position of the mobile terminal.

In the scriptures DE 10 2004 035 531 B4 For determining the position, an environment model (eg a cartographic model of the environment) is used to determine a current position on the basis of a current measured field strength and a position of the mobile terminal determined at an earlier point in time. The environment model preferably includes field strength values at reference points as well as logical movement possibilities in the environment. However, this does not take account of the fact that position is incorrectly estimated using the reference point field strength values in the environment model, or that the same field strength value can be measured at different positions, eg due to obstacles, etc. This can lead to errors and a wrong estimate of the position and thus of the follow-up positions.

In Scripture WO 2010/142692 A1 is also determined based on a characteristic of a signal which is transmitted in the radio network of access nodes, a position of a mobile terminal. This signal characteristic - ie the so-called RF fingerprint - is a characteristic measure for the radio environment, from which a position of a mobile terminal can be estimated on the basis of stored RF fingerprints, which correlate with known positions. However, this does not take into account that the same signal characteristics can be measured at several positions of an environment. The reason that the same signal characteristics can be measured at several positions is due in particular to deflected or diffracted signals. As a result, for example, signals from a nearby access node to the radio network can be received weaker by the mobile terminal than, for example, signals from more distant access nodes to which, so to speak, radio-controlled "line of sight" exists. Therefore, in comparison with reference values in a database and the consequent estimation of a current position of a mobile terminal, inaccuracies and / or errors may thereby occur determine the position or it will be estimated to the measured signal characteristics several possible positions where the mobile terminal could be located.

One possibility in the case of several possible positions is a current position of the mobile terminal in the radio network, e.g. for a use of a location-based application is a filtering - for example by means of a so-called Kalman filter. In this case, for example, a current position in the middle of the different determined position variants, e.g. estimated by mathematical methods to find a more possible position or on movement of the mobile terminal route. However, this can lead to greater inaccuracies in determining the position, especially if even less probable positions are taken into account.

Alternatively, a so-called Bayesian filter or Bayesian filter can be used for filtering at several possible positions. The Bayesian filter is a static filter based on the so-called Bayesian concept of probability. In doing so, when determining a current position of a mobile terminal in a radio network, e.g. also considers probabilities for future position as a function of past or already estimated positions. However, this does not take into account, for example, the possibility that misjudged estimates could have been made at positions that have already been estimated, which can lead to consequential errors and inaccuracies in the estimation of other positions.

Presentation of the invention

The invention is therefore based on the object of specifying a method for determining the position in a radio network, in which a current position of a mobile terminal is determined with high accuracy in a simple and efficient manner and without complex filtering.

The solution of this object is achieved by a method of the type described, in which at a time from a signal characteristic which has been determined for a position of a mobile terminal in a radio network, several probable, current positions are derived. Then probabilities for the current positions are determined from temporally adjacent position determinations and the most probable position is determined as the current position for the mobile terminal or the moving objects.

The main aspect of the method according to the invention is that in a sequence of measurements of the signal characteristic of the radio network by the mobile terminal, the measured values are combined at one time (eg a position of a route traveled by a mobile terminal with a set of measurements for that time) , Thus, measurements of the respective signal characteristic of each point are made along a route traveled by the mobile terminal, and from these measurements of the signal characteristic, a probability for the respectively possible current positions of the mobile terminal is determined. This results in a so-called "true-position" probability for each determined position in a given environment (e.g., company premises, shopping centers, etc.) - i. a probability that the mobile terminal or its user is actually in this position.

Then, the temporally adjacent positions are used in the method according to the invention to further refine the probabilities of the current positions. This means that adjacent positions are also likely to be in close proximity to each other when the mobile terminal is expected to move at a normal speed within a certain period of time (e.g., a person's normal walking speed, etc.). For example, the current position of the mobile terminal is determined by having an adjacent position with a high probability. In this way, a current position of a mobile terminal is determined with relatively high accuracy. It also includes past positions in addition to the current position in the position determination and thereby also possibly errors in determining the position - in particular from past positions - taken into account. That e.g. Changed or adjusted probabilities from already determined positions to obtain more accurate and better results in future position determinations.

It is advantageous in this case if a determination of the signal characteristic and the probable positions derived therefrom is carried out after a time interval has elapsed. Thus, a time for the measurement of the signal characteristic of the radio network and thus the determination of a position on a route traveled by the mobile terminal can be specified very easily. For example, a position determination or determination of the signal characteristic can always be carried out after a time interval of 10 seconds has elapsed. Thus, the signal characteristic determinations or the probable positions determined therefrom can simply be ranked in time, and in this way additionally a determination of the respectively most likely position on a route to be improved.

Ideally, statistical parameters of the signal characteristic are used to determine the probable positions. It is advantageous if, in particular, standard deviation, autocorrelation function, symmetry coefficient, curvature and / or a characteristic distribution function of the signal characteristic are used as static parameters. By using one or more of these static parameters of the signal characteristic for the position determination of a position, an even better accuracy for this position can be achieved. The static parameters are determined from the measurements of the signal characteristic for a position and then used these static parameters for the determination of the probable, current positions of the mobile terminal.

Furthermore, it is recommended that temporally adjacent determinations are weighted by probable positions. The weightings of a temporal and / or spatial distance of the positions are dependent on each other. Also by this measure, the accuracy of the position determination can be further improved and increased. It is particularly taken into account that a mobile terminal is likely to cover only a certain distance within a time span with high probability. Probable positions, e.g. have a large spatial distance to a temporally adjacent position, so for example less or hardly taken into account in the position determination. Likewise, e.g. Positions that are locally close but time-distant (e.g., outdated) are excluded.

It is expedient for the method according to the invention if, as signal characteristic, reception field strength values between the mobile terminal and a network node, in particular the so-called received signal strength indication (RSSI), are used. In a radio network, the reception field strength between a mobile terminal and a network node (e.g., base station, access point, etc.) has a particular value at each location of a particular area. If this area is covered by two or more network or access nodes, the reception field strength values result in a data record which is typical for this position as a signal characteristic, by means of which the position of the mobile terminal can be easily estimated.

The so-called Received Signal Strength Indication (RSSI) provides an indicator of the reception field strength in a radio network such. WirelessLAN, GSM, UMTS, CDMA, etc. This indicator is needed by a mobile terminal to find a channel useful for communication in a radio network. If the signal strength or reception field strength on a currently used channel falls below a certain required value, you can switch to another channel. The RSSI also has position-specific values in the radio network or, in the case of two or more network or access nodes, a position-specific data set of RSSI values can be derived therefrom, which can be used very simply as output information for determining the position of a mobile terminal. The RSSI technology is used in particular in radio networks such as WirelessLAN or Bluetooth and can therefore be used very easily, particularly in these radio networks for a position determination.

Alternatively, a so-called channel impulse response or channel state information (CSI) can advantageously be used as the signal characteristic. In radio communication, known channel characteristics of a communication connection are reproduced by the channel impulse response or by the channel state information (CSI). The CSI describes how a signal propagates between transmitter and receiver or mobile terminal and network or access node, with effects such as e.g. Scattering, attenuation / fading and power loss with distance or due to obstacles. The CSI is therefore used in radio networks, in particular in UMTS networks, to adapt transmissions to the current channel conditions. The CSI or channel impulse response also has position-dependent typical values and can thus be used for determining the position or for estimating probable positions of a mobile terminal. Furthermore, using the channel impulse response or the CSI as the signal characteristic offers the advantage that, in addition to a position determination with a very good accuracy, an environmental topology (for example, rooms, etc.) can also be estimated if necessary. To do this, however, it is necessary to evaluate a multipath profile (i.e., channel impulse responses between the mobile terminal and multiple network nodes).

As a signal characteristic but also ideally a bit or block error rate can be used. Bit and block error rates are quality characteristics for transmission on a digital transmission link. The bit error rate is, for example, a ratio of erroneously received bits and the number of bits received in the same time interval. These values can also have position-dependent characteristics and thus very easy for wireless networks with digital transmission Estimating possible positions of a mobile terminal are used.

But it is also possible that the signal characteristic consists of a combination of received field strength values, channel impulse response and / or bit or block error rate. By the appropriate combination of received field strength values, channel impulse responses, and / or bit / block error rate - if all or more of these values are supported by the respective radio network - the position determination can be made even more accurate and possibly also easily a topology of the environment of the mobile terminal can be estimated ,

It is favorable if a so-called wireless LAN or WLAN or Bluetooth network is used as the radio network. It can be used as a radio network but also a radio network based on various radio network standards such as UMTS, GSM, TETRA, CDMA, LTE, WiMAX or APCo-P25. Thus, with the method according to the invention, a position determination of a mobile terminal can be carried out in a simple manner in the common and widespread radio networks.

Brief description of the drawing

The invention is explained schematically below by way of example with reference to the attached figure. 1 shows schematically and exemplarily a flow of the inventive method for determining the position of a mobile terminal in a radio network.

Embodiment of the invention

1 schematically shows an exemplary radio network FN. This radio network FN can, for example, be a so-called wireless LAN and comprises three exemplary access nodes AP1, AP2, AP3, which cover an area symbolically represented by circles. Alternatively, the radio network FN may also be a radio network FN based on UMTS, CDMA or GSM standard. Then, the three exemplary access nodes AP1, AP2, AP3 would be base stations of the radio network FN covering an area bounded by the exemplary circle lines. However, the method according to the invention can equally be executed in other radio networks FN such as Bluetooth or radio network FN on the basis of the TETRA standard, LTE standards, WiMAX standards or APCO P25 standards.

In the radio network FN are located at different positions P1, P2 mobile terminals MP1, MP2. In this case, a first mobile terminal MP1 is at a first position P1 of the radio network FN. A second mobile terminal MP2 is located at a second position P2 of the radio network. In this case, the respective positions P1, P2 of the mobile terminals have different signal characteristics SC1, SC2. These signal characteristics SC1, SC2 can be, for example, a set of received field strength values or a Received Signal Strength Indication (RSSI) determinable at the respective position P1, P2, which can be established between the respective terminal MP1, MP2 and the respective access or network node AP1, AP2, AP3 can be measured. As a signal characteristic SC1, SC2 but also a so-called channel impulse response or channel state information - in particular in a radio network FN based on the UMTS standard - are used. Furthermore, a use of bit error rate or block error rate as a signal characteristic SC1, SC2 is conceivable. A combination of received field strength, channel impulse response and / or bit / block error rate as signal characteristic SC1, SC2 is also possible, provided that these parameters are supported or made available by the respective radio network FN.

In a first process step 1 is from the respective mobile terminal MP1, MP2 at a time t a corresponding signal characteristic SC1, SC2 at the position P1, P2 of the radio network FN, at which the respective mobile terminal MP1, MP2 is performed. For example, measurements of parameters such as the reception field strength or RSSI or the channel impulse response to the network nodes AP1, AP2, AP3 are carried out by the first mobile terminal MP1 at the position P1 for the time t. This results in a signal characteristic SC1 for the position P1 of the first mobile terminal MP1. For example, in order to be able to track a movement route of the first mobile terminal, the position-dependent measurements of the respective signal characteristic SC1 are carried out after a time interval of, for example, 10 seconds. That is, for example, a signal characteristic SC1 is determined by the first mobile terminal MP1 every 10 seconds in order to derive therefrom positions P1 for the first mobile terminal MP1.

From the second mobile terminal MP2 at the position P2, a determination of the signal characteristic SC2 belonging to this position P2 is likewise carried out at a (different) point in time. For the sake of simplicity, the further course of the method according to the invention will be explained on the basis of the first mobile terminal MP1 or based on the first position P1 of the first mobile terminal MP1.

From the first step 1 The signal characteristic SC1 determined by the first terminal MP1 for the current position P1 of the first mobile terminal MP1 is then used in a second method step 2 for example with the aid of a database DB (eg a Radio Field Intensity Database, etc.) determines possible or probable current positions P11, P12, P13 for the first mobile terminal MP1. Then in a third process step 3 determined for the determined possible current positions P11, P12, P13 of the first mobile terminal probabilities. The possible current positions P11, P12, P13 can then be stored in a matrix, for example for the time t of measurement of the associated signal characteristic SC1.

From this matrix, past positions Pv1, Pv1 of the first mobile terminal MP1 with the corresponding probabilities are also apparent. In 1 For the sake of simplicity, only a bygone date is shown. In the third process step 3 In the determination of the probabilities of possible current positions P11, P12, P13 of the first mobile terminal MP1, the temporally adjacent positions Pv1, Pv2 are also taken into account. That is, if, for example, there is a temporally adjacent position Pv1 with a high probability that this position was an actual position of the mobile terminal MP1 at the time of the measurement, and if this position Pv1 would be close to and / or locally close to one of the possible times, for example current positions P11, P12, P13, this may increase the probability of this possible current position P11, P12, P13.

In the in 1 In the example shown, the probability of the possible current position P12 is influenced by the temporally adjacent position Pv1. In this case, temporally adjacent determinations of probable positions Pv1, Pv2, P11, P12, P13 can be weighted correspondingly, wherein a respective temporal and / or spatial distance of the positions Pv1, Pv2, P11, P12, P13 from one another can be used as the respective weighting. In this case, it is additionally taken into account that a mobile terminal can only be moved over a certain distance within a time span, for example the time span between the measurement of the past possible positions Pv1, Pv2 and the determination of the current, possible positions P11, P12, P13.

It is advantageous to consider existing obstacles when determining spatially adjacent points. For example, the accuracy of the method can be improved if each route contains only possible paths. For example, in a building, for the determination of a probable route, only points within a room or points connected by doors are allowed. Furthermore, possible transitions to neighboring points can be weighted with probabilities.

In a fourth process step 4 The most probable position P12 is then determined on the basis of the probabilities of the past positions Pv1, Pv2 or based on these past positions Pv1, Pv2 and the derived probabilities of the possible current positions P11, P12, P13 and set as the current position P1 of the first mobile terminal MP1. By the method or the consideration of past possible positions Pv1, Pv2, the accuracy is increased or an error rate is reduced - in particular if starting positions of routes of mobile terminals MP1, MP2 are to be determined. In order to additionally increase the accuracy of the method, for the determination of the probable current positions P11, P12, P13 in the second method step 2 static parameters of the signal characteristic SC1 be used instead of the signal characteristic SC1. Conceivable statistical parameters are, for example, standard deviation, autocorrelation function, symmetry coefficient, curvature and / or a characteristic distribution function of the signal characteristic SC1.

The inventive method relatively accurately position determinations of mobile terminals MP1, MP2 in radio networks FN with e.g. achieved an accuracy of about 3 to 5 meters. The method can therefore ideally be applied to location-dependent services and applications used in indoor areas, e.g. Shopping centers, company premises, large buildings to be applied, are used. Such applications are e.g. Sending location-dependent information (e.g., sales promotion, advertising, coupons, etc.), navigation and guidance services e.g. in large public buildings, on company premises, etc., location-dependent information services (e.g., museum, etc.) or user-specific applications (e.g., search / find applications).

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102004035531 B4 [0011, 0012]
• WO 2010/14692 A1 [0011]
• WO 2010/142692 A1 [0013]

Claims (10)

Method for determining position in a radio network, wherein a signal characteristic (SC1, SC2) of the radio network (FN) at a position (P1, P2) is determined by a mobile terminal (MP1, MP2) ( 1 ), and from this an information about this position (P1, P2) is derived, characterized in that a plurality of probable, current positions (P11, P12, P13) are determined at a time (t) from the signal characteristic (SC1) ( 2 ) that then from temporally adjacent position determinations (Pv1, Pv2) probabilities for the current positions (P11, P12, P13) are derived ( 3 ), and that the most probable position (P12) is set as the current position (P1) ( 4 ). Method according to Claim 1, characterized in that a determination of the signal characteristic (SC1, SC2) and the probable positions (P11, P12, P13) derived therefrom are carried out after a time interval (t) has elapsed ( 2 . 3 ). Method according to one of claims 1 to 3, characterized in that for a determination of the probable positions (P11, P12, P13) statistical parameters of the signal characteristic (SC1, SC2) are used. A method according to claim 3, characterized in that are used as statistical parameters in particular standard deviation, autocorrelation function, symmetry coefficient, curvature and / or a characteristic distribution function of the signal characteristic (SC1, SC2). Method according to one of claims 1 to 4, characterized in that temporally adjacent determinations (Pv1, Pv2) of probable positions (P11, P12, P13) are weighted, wherein a respective weighting depends on a temporal and / or spatial distance of the respective positions (Pv1, Pv2, P11, P12, P13) to each other. Method according to one of claims 1 to 5, characterized in that the signal characteristic (SC1, SC2) receiving field strength values between the mobile terminal (MP1, MP2) and a network node (AP1, AP2, AP3), in particular the so-called received signal strength indication ( RSSI). Method according to one of Claims 1 to 6, characterized in that a so-called channel impulse response or channel state information (CSI) is used as the signal characteristic (SC1, SC2). Method according to one of claims 1 to 7, characterized in that a so-called bit or block error rate is used as the signal characteristic (SC1, SC2). Method according to one of Claims 1 to 8, characterized in that the signal characteristic (SC1, SC2) used is a combination in which received field strength values, channel impulse responses, and / or bit / block error rate are combined. Method according to one of Claims 1 to 9, characterized in that the wireless network (FN) is WirelessLAN or Bluetooth or a radio network based on UMTS, GSM, TETRA, CDMA, LTE, WiMAX or APCO-P25 standards is used.

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